1. Field of the Invention
The present invention relates to a catalytic converter including an improved mechanism for feeding a part of the make-up gas to control the reaction temperature.
2. Description of the Prior Art
British Pat. No. 1,105,614 discloses a catalytic converter of the fixed bed type including intermediate fluid injection means therein, said intermediate fluid injection means each comprising a number of perforated hollow bars which incorporate spargers for fluid injection, wherein said hollow bars are large enough in cross section to constitute a fluid mixing zone and are arranged so close to each other or to the wall of a converter that a substantial portion of the reaction mixture is passed through the inside of the hollow bars. By using a converter of this type, the reaction temperature can easily be controlled to the required level.
A converter of this type, however, has the disadvantages as described hereunder. First of all, the fluid is fed to the perforated hollow bars through the nozzles (or inlet ports) provided on the side wall of the pressure-retaining shell or the lid of the reactor so that one nozzle is necessary for each of the perforated hollow bars in the case of feeding fluid through the side wall or a plurality of nozzles are necessary for each of the perforated hollow bars (C-shape or ring type) in order to assure uniform distribution of fluid therein in the case of feeding fluid through the lid.
As a plurality of perforated tubes must be installed in several stages in the direction of the reactant flow, a large number of nozzles are required to be provided on the side wall of the pressure-retaining shell or the lid. However, as a large-scale catalytic converter of this type imposed many restrictions in the design, fabrication, transportation and the like, of converter vessels, the converter vessel is desired to have as few nozzles as possible.
Second, support rings must be provided, which are welded onto the inside of the pressure-retaining shell of the converter, in order to support the perforated hollow bars to be disposed in parallel with proper clearance in a predetermined sectional space. A larger converter generally requires a thicker wall of its pressure-retaining shell, with the welding of support rings onto such a thicker wall possibly causing weld cracks on the wall. Furthermore, if the diameter of the reactor becomes larger, the perforated hollow bars become longer, rendering the length of the support span larger. This tends to necessitate an increase in the rigidity of the perforated hollow bars. It is possible to alleviate the situation by supporting the hollow bars with a plurality of beams being placed under and in the direction perpendicular to the hollow bars. However, this arrangement requires longer supporting beams which must have greater rigidity and consequently must be the bigger. The bigger size of the beams prevents reactants from flowing uniformly along the converter vessel axis. Furthermore, the supporting of the perforated hollow bars of C-shape or ring type requires a plurality of beams thereunder, which involves such disadvantages as described above.
Third, as the size of beams for supporting perforated hollow bars becomes larger, the effective space for reaction in a converter is reduced accordingly. In case the perforated hollow bars are C-shape or ring type, plurality a of connecting tubes must be installed for each set of the perforated hollow bars passing through the lid to the inside of a reactor, and thus the plurality of connecting tubes reduces the effective space for the reaction of the converter accordingly.